Recently, frequency-sharing wireless communications have been needed in wireless communication fields. FIG. 20 is a conceptual illustration showing an example of a combination of wireless communication systems sharing frequency bands, i.e. the overall constitution implementing two wireless LAN (Local Area Network) systems having different frequency channels.
In this illustration, the wireless communication system includes wireless LAN stations 2a, 2b and a receiver 1a. The wireless LAN station 2a performs communication using a frequency band CH1 having a center frequency fa. The wireless LAN station 2b performs communication using a frequency band CH5 having a center frequency fb (where fa<fb).
The receiver 1a is arranged at a position, which is reachable by both the wireless signals from the wireless LAN stations 2a, 2b, so as to receive signals in which two wireless signals, i.e. the wireless signal of the center frequency fa and the wireless signal of the center frequency fb, partially overlap with each other.
There are other examples of sharing frequency bands, in which different communication systems share frequencies, such as a combination of a wireless LAN system, Bluetooth (a registered trademark) and WiMax (a registered trademark).
In the case of FIG. 20 in which the receiver 1a assumes the wireless LAN station 2a as a communication target, it is prerequisite for the receiver 1a to precisely receive a desired wave in a frequency-sharing wireless communication in which a transmission frequency band of a desired wave having the center frequency fa partially overlaps with a transmission frequency band of an interference wave having the center frequency fb from the wireless LAN station 2b. 
There is a technology (e.g. Non-Patent Document 1) in which a plurality of multicarrier wireless communication systems cooperate with each other and in which different sub-carriers are allocated as sub-carriers having a possibility of interfering with other systems via scheduling and setting so as to improve frequency utilization efficiency in a certain frequency band maintaining a certain level of D/U (Desired to Undesired signal ratio) representing the ratio of intensity between a desired wave and an interference wave, for example.
In addition, a multistage interference cancellation method (e.g. Non-Patent Documents 2, 3) has been developed with respect to a reception signal (D+U1+U2+U3+ . . . ) in which a desired wave D is added to a plurality of interference waves U1, U2, U3, . . . in a receiver side. In this interference cancellation method, interference replicas U1′, U2′, U3′, . . . , i.e. estimate values regarding a plurality of interference waves U1, U2, U3, . . . , are calculated (produced) in advance, whereby the desired wave D is calculated according to the following procedures.                First step: Reception signal (D+U1+U2+U3+ . . . )−interference replica U1′≈signal (D+U2+U3+ . . . )        Second step: Signal (D+U2+U3+ . . . )−interference replica U2′≈signal (D+U3+ . . . )        Third step: Signal (D+U3+ . . . )−interference replica U3′≈signal (D+ . . . )        
That is, the receiver successively subtracts the calculated interference replicas U1′, U2′, . . . from the reception signal (D+U1+U2+U3+ . . . ) so as to calculate the desired wave D.